Planthopper is an insect belonging to Delphacidae, and 1800 species of which have been identified so far. The body is 2˜9 mm long and it has a short head. It has simple antennas and short front wings. The wing vein is degenerated. It has movable spinous processes at the end of the hind leg calf segment. The planthopper lives on various plants and both adults and larvae are harmful to crops such as rice, barley, corn, and sugar cane. Many adults and larvae secrete white waxy materials from the abdomen or back of the body. The adults that are active in winter can be observed in the southern part of Korea and in the islands of southern sea. The planthopper is distributed world-widely basically along the tropical area. In Korea, 33 species of the planthopper including brown planthopper, whitebacked planthopper, and small brown planthopper are distributed.
Among them, the whitebacked planthopper has a dark brown body and the female has a brighter colored body than the male. It has a long grayish yellow pattern in the middle of the waist. This insect is harmful to rice and barley by carrying dwarf to them. Like the brown planthopper, the whitebacked planthopper cannot stay over winter in Korea and flies from the southern part of China every year. The population of the whitebacked planthopper flying over from China is 10 times larger than the brown planthopper but the damage is not focused on a certain area but spread instead, which seems less serious. The life of one generation of the whitebacked planthopper is about 24 days at 25° C., more precisely, the before spawning period is 4.6 days, the spawning period is 7.6 days, and the spawning period is 13 days. In the outdoor temperature between June and August, it spends one generation in 20˜30 days. The life span of the adult is 15.6 days, the number of eggs is about 250, and the egg lay on the leaf sheath. The adult lays about 250 eggs in a pile on a plant leaf.
Flavonoids are a class of plant and fungus secondary metabolites. Chemically, flavonoids have the general structure of a 15-carbon skeleton, which consists of two phenyl rings (A and B) and heterocyclic ring (C).
Cochlioquinone (C30H44O8) is one of the flavonoids and is the main component of the living pigments isolated from Bipolarisleersia. It is known that cochlioquinone can be used as an antagonist of the human chemokine receptor CCR5 in human immunodeficiency virus type 1 (HIV-1). Cochlioquinone has been confirmed to have the activity of anti-angiogenesis and to inhibit diacylglycerol acyltransferase and NADH ubiquinone reductase.
Chrysoeriol (C16H12O6) is one of the flavonoids and is a component mainly contained in Eriodyctionglutinosum Bentham leaves. It is a yellow needle like crystal and is melted at 337° C. It is hardly dissolved in ethyl acetate and ethanol, but is easily melted in hot pyridine. Chrysoeriol is known to have the activity of lowering lipid concentration.
There are many methods for the separation or isolation of cochlioquinone and chrysoeriol reported so far but they cost a lot and the production efficiency is very low. Therefore, it is requested to develop a novel separation method.